Ovulation Calculator
Find your estimated ovulation date and fertile window
Frequently Asked Questions
Ovulation typically occurs about 14 days before your next period starts. This calculator estimates it as your cycle length minus 14 days, counted from the first day of your last period.
It's roughly the 5 days before ovulation plus the day of ovulation itself, since sperm can survive in the reproductive tract for several days while the egg is viable for about 24 hours after release.
This calculator gives a rough estimate based on average cycle length. If your cycles vary significantly month to month, ovulation predictor kits or tracking basal body temperature give more accurate real-time results than a date-based estimate alone.
The 2-3 days leading up to and including ovulation day generally offer the highest chance of conception, since they align sperm availability with the egg's release.
How this is calculated
Ovulation date = first day of last period + (cycle length − 14). Fertile window = 5 days before ovulation through the day after ovulation. Next period = last period + cycle length.